3
3.0
Jun 30, 2018
06/18
by
Sibylle Meyer; Matthias Althammer; Stephan Geprägs; Matthias Opel; Rudolf Gross; Sebastian T. B. Goennenwein
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We study the temperature dependence of the spin Hall magnetoresistance (SMR) in yttrium iron garnet/platinum hybrid structures via magnetization orientation dependent magnetoresistance measurements. Our experiments show a decrease of the SMR magnitude with decreasing temperature. Using the sensitivity of the SMR to the spin transport properties of the normal metal, we interpret our data in terms of a decrease of the spin Hall angle in platinum from 0.11 at room temperature to 0.075 at 10K,...
Topics: Mesoscale and Nanoscale Physics, Condensed Matter
Source: http://arxiv.org/abs/1401.7787
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14
Jun 28, 2018
06/18
by
Sebastian T. B. Goennenwein; Richard Schlitz; Matthias Pernpeintner; Matthias Althammer; Rudolf Gross; Hans Huebl
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eye 14
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We study the local and non-local magnetoresistance of thin Pt strips deposited onto yttrium iron garnet. The local magnetoresistive response, inferred from the voltage drop measured along one given Pt strip upon current-biasing it, shows the characteristic magnetization orientation dependence of the spin Hall magnetoresistance. We simultaneously also record the non-local voltage appearing along a second, electrically isolated, Pt strip, separated from the current carrying one by a gap of a few...
Topics: Mesoscale and Nanoscale Physics, Condensed Matter, Materials Science
Source: http://arxiv.org/abs/1508.06130
4
4.0
Jun 29, 2018
06/18
by
Sabine Pütter; Stephan Geprägs; Richard Schlitz; Matthias Althammer; Andreas Erb; Rudolf Gross; Sebastian T. B. Goennenwein
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We study the influence of the interface quality of Pt/Y$_3$Fe$_5$O$_{12}$(111) hybrids on their spin Hall magnetoresistance. This is achieved by exposing Y$_3$Fe$_5$O$_{12}$(111) single crystal substrates to different well-defined surface treatments prior to the Pt deposition. The quality of the Y$_3$Fe$_5$O$_{12}$(YIG) surface, the Pt/YIG interface and the Pt layer is monitored \textit{in-situ} by reflection high-energy electron diffraction and Auger electron spectroscopy as well as...
Topics: Mesoscale and Nanoscale Physics, Condensed Matter
Source: http://arxiv.org/abs/1612.08150
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86
Sep 20, 2013
09/13
by
Matthias Althammer; Eva-Maria Karrer-Müller; Sebastian T. B. Goennenwein; Matthias Opel; Rudolf Gross
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The wide bandgap semiconductor ZnO is interesting for spintronic applications because of its small spin-orbit coupling implying a large spin coherence length. Utilizing vertical spin valve devices with ferromagnetic electrodes (TiN/Co/ZnO/Ni/Au), we study the spin-polarized transport across ZnO in all-electrical experiments. The measured magnetoresistance agrees well with the prediction of a two spin channel model with spin-dependent interface resistance. Fitting the data yields spin diffusion...
Source: http://arxiv.org/abs/1205.3666v3
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12
Jun 28, 2018
06/18
by
Yan-Ting Chen; Saburo Takahashi; Hiroyasu Nakayama; Matthias Althammer; Sebastian T. B. Goennenwein; Eiji Saitoh; Gerrit E. W. Bauer
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We review the recently discovered spin Hall magnetoresistance (SMR) and related effects from a theoretical point of view. The SMR is observed in bilayers of a magnetic insulator and a metal, in which spin currents aregenerated in the normal metal due to the spin Hall effect. The associated angular momentum transfer to the ferromagnetic layer and thereby the electrical resistance is modulated by the angle between the applied current and the magnetization direction. The SMR provides a convenient...
Topics: Mesoscale and Nanoscale Physics, Condensed Matter, Materials Science
Source: http://arxiv.org/abs/1507.06054
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92
Sep 21, 2013
09/13
by
A. Nielsen; A. Brandlmaier; M. Althammer; W. Kaiser; M. Opel; J. Simon; W. Mader; S. T. B. Goennenwein; R. Gross
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Oxide based ferromagnet/semiconductor heterostructures offer substantial advantages for spin electronics. We have grown (111) oriented Fe3O4 thin films and Fe3O4/ZnO heterostructures on ZnO(0001) and Al2O3(0001) substrates by pulsed laser deposition. High quality crystalline films with mosaic spread as small as 0.03 degree, sharp interfaces, and rms surface roughness of 0.3 nm were achieved. Magnetization measurements show clear ferromagnetic behavior of the magnetite layers with a saturation...
Source: http://arxiv.org/abs/0808.2245v1
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12
Jun 29, 2018
06/18
by
Matthias Althammer; Amit Vikam Singh; Sahar Keshavarz; Mehmet Kenan Yurtisigi; Rohan Mishra; Albina Borisevich; Patrick LeClair; Arunava Gupta
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We experimentally investigate the structural, magnetic and electrical transport properties of La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ based magnetic tunnel junctions with a SrSnO$_3$ barrier. Our results show that despite the large number of defects in the strontium stannate barrier, due to the large lattice mismatch, the observed tunnel magnetoresistance is comparable to tunnel junctions with a better lattice matched STiO$_3$ barrier, reaching values of up to 350% at T=5 K. Further analysis of the...
Topics: Mesoscale and Nanoscale Physics, Condensed Matter
Source: http://arxiv.org/abs/1607.08393
4
4.0
Jun 29, 2018
06/18
by
Matthias Althammer; Joynarayan Mukherjee; Stephan Geprägs; Sebastian T. B. Goennenwein; Matthias Opel; M. S. Ramachandra Rao; Rudolf Gross
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We study the flow of a pure spin current through zinc oxide by measuring the spin Hall magnetoresistance (SMR) in thin film trilayer samples consisting of bismuth-substituted yttrium iron garnet (Bi:YIG), gallium-doped zinc oxide (Ga:ZnO), and platinum. We investigate the dependence of the SMR magnitude on the thickness of the Ga:ZnO interlayer and compare to a Bi:YIG/Pt bilayer. We find that the SMR magnitude is reduced by almost one order of magnitude upon inserting a Ga:ZnO interlayer, and...
Topics: Mesoscale and Nanoscale Physics, Condensed Matter
Source: http://arxiv.org/abs/1612.07239
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93
Sep 22, 2013
09/13
by
Yan-Ting Chen; Saburo Takahashi; Hiroyasu Nakayama; Matthias Althammer; Sebastian T. B. Goennenwein; Eiji Saitoh; Gerrit E. W. Bauer
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We present a theory of the spin Hall magnetoresistance (SMR) in multilayers made from an insulating ferromagnet F, such as yttrium iron garnet (YIG), and a normal metal N with spin-orbit interactions, such as platinum (Pt). The SMR is induced by the simultaneous action of spin Hall and inverse spin Hall effects and therefore a non-equilibrium proximity phenomenon. We compute the SMR in F$|$N and F$|$N$|$F layered systems, treating N by spin-diffusion theory with quantum mechanical boundary...
Source: http://arxiv.org/abs/1302.1352v1
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71
Sep 22, 2013
09/13
by
Deepak Venkateshvaran; Wolfgang Kaiser; Andrea Boger; Matthias Althammer; M. S. Ramachandra Rao; Sebastian T. B. Goennenwein; Matthias Opel; Rudolf Gross
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The anomalous Hall effect (AHE) has been studied systematically in the low-conductivity ferromagnetic oxide Fe$_{3-x}$Zn$_x$O$_4$ with $x = 0$, 0.1, and 0.5. We used (001), (110), and (111) oriented epitaxial Fe$_{3-x}$Zn$_x$O$_4$ films grown on MgO and sapphire substrates in different oxygen partial pressure to analyze the dependence of the AHE on crystallographic orientation, Zn content, strain state, and oxygen deficiency. Despite substantial differences in the magnetic properties and...
Source: http://arxiv.org/abs/0805.1120v1
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62
Sep 21, 2013
09/13
by
Deepak Venkateshvaran; Matthias Althammer; Andrea Nielsen; Stephan Gepraegs; M. S. Ramachandra Rao; Sebastian T. B. Goennenwein; Matthias Opel; Rudolf Gross
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The ferrimagnetic spinel oxide Zn(x)Fe(3-x)O(4) combines high Curie temperature and spin polarization with tunable electrical and magnetic properties, making it a promising functional material for spintronic devices. We have grown epitaxial thin films with 0
Source: http://arxiv.org/abs/0808.3642v3
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68
Sep 23, 2013
09/13
by
M. Weiler; A. Brandlmaier; S. Gepraegs; M. Althammer; M. Opel; C. Bihler; H. Huebl; M. S. Brandt; R. Gross; S. T. B. Goennenwein
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The control of magnetic properties by means of an electric field is an important aspect in magnetism and magnetoelectronics. We here utilize magnetoelastic coupling in ferromagnetic/piezoelectric hybrids to realize a voltage control of magnetization orientation at room temperature. The samples consist of polycrystalline nickel thin films evaporated onto piezoelectric actuators. The magnetic properties of these multifunctional hybrids are investigated at room temperature as a function of the...
Source: http://arxiv.org/abs/0810.0389v1
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6.0
Jun 29, 2018
06/18
by
Kathrin Ganzhorn; Joseph Barker; Richard Schlitz; Matthias Althammer; Stephan Geprägs; Hans Huebl; Benjamin A. Piot; Rudolf Gross; Gerrit E. W. Bauer; Sebastian T. B. Goennenwein
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We study the spin Hall magnetoresistance effect in ferrimagnet/normal metal bilayers, comparing the response in collinear and canted magnetic phases. In the collinear magnetic phase, in which the sublattice magnetic moments are all aligned along the same axis, we observe the conventional spin Hall magnetoresistance. In contrast, in the canted phase, the magnetoresistance changes sign. Using atomistic spin model calculations of the magnetic configuration, we show that the electric transport for...
Topics: Mesoscale and Nanoscale Physics, Condensed Matter
Source: http://arxiv.org/abs/1605.07441
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143
Jul 20, 2013
07/13
by
C. Bihler; M. Althammer; A. Brandlmaier; S. Gepraegs; M. Weiler; M. Opel; W. Schoch; W. Limmer; R. Gross; M. S. Brandt; S. T. B. Goennenwein
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We have investigated the magnetic properties of a piezoelectric actuator/ferromagnetic semiconductor hybrid structure. Using a GaMnAs epilayer as the ferromagnetic semiconductor and applying the piezo-stress along its [110] direction, we quantify the magnetic anisotropy as a function of the voltage V_p applied to the piezoelectric actuator using anisotropic magnetoresistance techniques. We find that the easy axis of the strain-induced uniaxial magnetic anisotropy contribution can be inverted...
Source: http://arxiv.org/abs/0804.1336v1
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66
Sep 23, 2013
09/13
by
Mathias Weiler; Matthias Althammer; Franz D. Czeschka; Hans Huebl; Martin S. Wagner; Matthias Opel; Inga-Mareen Imort; Günter Reiss; Andy Thomas; Rudolf Gross; Sebastian T. B. Goennenwein
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A scannable laser beam is used to generate local thermal gradients in metallic (Co2FeAl) or insulating (Y3Fe5O12) ferromagnetic thin films. We study the resulting local charge and spin currents that arise due to the anomalous Nernst effect (ANE) and the spin Seebeck effect (SSE), respectively. In the local ANE experiments, we detect the voltage in the Co2FeAl thin film plane as a function of the laser spot position and external magnetic field magnitude and orientation. The local SSE effect is...
Source: http://arxiv.org/abs/1110.3981v1
8
8.0
Jun 30, 2018
06/18
by
Stephan Geprägs; Andreas Kehlberger; Tomek Schulz; Christian Mix; Francesco Della Coletta; Sibylle Meyer; Akashdeep Kamra; Matthias Althammer; Gerhard Jakob; Hans Huebl; Rudolf Gross; Sebastian T. B. Goennenwein; Mathias Kläui
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We probe the spin Seebeck effect in Gd$_{3}$Fe$_{5}$O$_{12}$/Pt hybrid structures as a function of temperature and observe two sign changes of the spin Seebeck signal with decreasing temperature. A first sign change occurs at a temperature close to the Gd$_{3}$Fe$_{5}$O$_{12}$ magnetic compensation point at around 280 K. There the spin Seebeck signal changes sign abruptly with unaltered amplitude, indicating that the spin current is mainly caused by the magnetic Fe sub-lattices, which reorient...
Topics: Mesoscale and Nanoscale Physics, Condensed Matter
Source: http://arxiv.org/abs/1405.4971
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56
Sep 23, 2013
09/13
by
F. D. Czeschka; L. Dreher; M. S. Brandt; M. Weiler; M. Althammer; I. -M. Imort; G. Reiss; A. Thomas; W. Schoch; W. Limmer; H. Huebl; R. Gross; S. T. B. Goennenwein
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We systematically measured the DC voltage V_ISH induced by spin pumping together with the inverse spin Hall effect in ferromagnet/platinum bilayer films. In all our samples, comprising ferromagnetic 3d transition metals, Heusler compounds, ferrite spinel oxides, and magnetic semiconductors, V_ISH invariably has the same polarity. V_ISH furthermore scales with the magnetization precession cone angle with a universal prefactor, irrespective of the magnetic properties, the charge carrier transport...
Source: http://arxiv.org/abs/1012.3017v2
4
4.0
Jun 30, 2018
06/18
by
Daniel Meier; Daniel Reinhardt; Michael van Straaten; Christoph Klewe; Matthias Althammer; Michael Schreier; Sebastian T. B. Goennenwein; Arunava Gupta; Maximilian Schmid; Christian H. Back; Jan-Michael Schmalhorst; Timo Kuschel; Günter Reiss
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We investigate the inverse spin Hall voltage of a 10nm thin Pt strip deposited on the magnetic insulators Y3Fe5O12 (YIG) and NiFe2O4 (NFO) with a temperature gradient in the film plane. We observe characteristics typical of the spin Seebeck effect, although we do not observe a change of sign of the voltage at the Pt strip when it is moved from hot to cold side, which is believed to be the most striking feature of the transverse spin Seebeck effect. Therefore, we relate the observed voltages to...
Topics: Materials Science, Condensed Matter
Source: http://arxiv.org/abs/1411.6790
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71
Sep 22, 2013
09/13
by
Matthias Opel; Stephan Gepraegs; Edwin P. Menzel; Andrea Nielsen; Daniel Reisinger; Karl-Wilhelm Nielsen; Andreas Brandlmaier; Franz D. Czeschka; Matthias Althammer; Mathias Weiler; Sebastian T. B. Goennenwein; Juergen Simon; Matthias Svete; Wentao Yu; Sven-Martin Huehne; Werner Mader; Rudolf Gross
texts
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Transition metal oxides show fascinating physical properties such as high temperature superconductivity, ferro- and antiferromagnetism, ferroelectricity or even multiferroicity. The enormous progress in oxide thin film technology allows us to integrate these materials with semiconducting, normal conducting, dielectric or non-linear optical oxides in complex oxide heterostructures, providing the basis for novel multi-functional materials and various device applications. Here, we report on the...
Source: http://arxiv.org/abs/1001.4447v2
175
175
Jul 20, 2013
07/13
by
Matthias Althammer; Sibylle Meyer; Hiroyasu Nakayama; Michael Schreier; Stephan Altmannshofer; Mathias Weiler; Hans Huebl; Stephan Geprägs; Matthias Opel; Rudolf Gross; Daniel Meier; Christoph Klewe; Timo Kuschel; Jan-Michael Schmalhorst; Günter Reiss; Liming Shen; Arunava Gupta; Yan-Ting Chen; Gerrit E. W. Bauer; Eiji Saitoh; Sebastian T. B. Goennenwein
texts
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We experimentally investigate and quantitatively analyze the spin Hall magnetoresistance effect in ferromagnetic insulator/platinum and ferromagnetic insulator/nonferromagnetic metal/platinum hybrid structures. For the ferromagnetic insulator we use either yttrium iron garnet, nickel ferrite or magnetite and for the nonferromagnet copper or gold. The spin Hall magnetoresistance effect is theoretically ascribed to the combined action of spin Hall and inverse spin Hall effect in the platinum...
Source: http://arxiv.org/abs/1304.6151v1
147
147
Aug 24, 2015
08/15
by
Peter J. Althammer
audio
eye 147
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mp3 audio
Topics: ambient, soundscapes, instrumental
147
147
Aug 26, 2015
08/15
by
Peter J. Althammer
audio
eye 147
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mp3 audio
Topics: ambient, soundscapes, instrumental, electronic
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57
Aug 26, 2015
08/15
by
Peter J. Althammer
image
eye 57
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album cover
Topic: album cover
127
127
Aug 24, 2015
08/15
by
Peter J. Althammer
audio
eye 127
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mp3 audio
Topics: ambient, soundscapes, intrumental
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141
Aug 25, 2015
08/15
by
Peter J. Althammer
audio
eye 141
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mp3 audio
Topics: ambient, soundscapes, instrumental
